스마트 횡단보도 조명 시스템의 시인성 및 안전성 향상에 관한 연구

Abstract

ABSTRACT

A Study on Improvement of Visibility and Safety of Smart Crosswalk Lighting System

Kim Hoo Sung Advisor : Prof. Yong-Jae Kim, Ph. D. Department of Electrical Enginnering Graduate School of Chosun University

According to the pedestrian accident statistics of 2015, "crossing (24.8%)" and "crossing near crosswalk (4.8%)" accounted for about 30% of crosswalk pedestrian accidents. Including "other crossing (24.6%)" would result in more than half of all pedestrian accidents. This suggests that there is a need to ensure visibility of the light distribution within the crosswalk. According to the analysis of characteristics of children's traffic accidents in school zone (National Police Agency, 2013), the number of cases occurred in the order of road 타입 (42.2%), crosswalk (27.3%), and intersection (11.7%). The deaths were in the order of crosswalk (34.6%), bridge (26.9%), and intersection (19.2%). This suggests that a responsive crosswalk should be installed to give the pedestrian a warning that pedestrians might not enter the roadway at the stop signal. No products conform to the domestic KS standards for crosswalk luminaires. It is necessary to install a product that satisfies the installation criteria according to the guidelines of the Ministry of Land, Transport and Logistics. Currently, there is no LED crosswalk luminaires registered at the Korean Resource Center of the Public Procurement Service, and small and medium enterprises are developing LED crosswalk lighting systems with cut-off light distribution and dimming control. In the dimming control, the method of detecting and controlling the brightness is the best method, but there is no practicality because the luminance system is expensive. Most products are controlling the intensity of light through the current control. 2,391 patents related to LED light distribution and pedestrian LED lighting were searched. Among them, 20 patents with high relevance were analyzed. As a result, three patents were identified as the most important patents. Currently, there are no LED crosswalk lighting system registered, and LED crosswalk lighting system through cut-off light distribution and dimming control has been studied centered on small and medium enterprises. Most LED crosswalk luminaires currently used in pedestrian crosswalks use LED floodlights in accordance with the "KS C 7717" regulations due to the difficulty of implementing cut-off light distribution. However, the lighting effect is weak and it causes a traffic accident caused by glare, rather than causing a light pollution. According to the Ministry of Land Transportation Guidelines, revised in 2014, the minimum horizontal surface roughness remains at a level of 6 lx. Because of this, compared to 24 lx, which can distinguish objects, it is not enough. In addition, because it is illuminated without taking into account weather conditions such as snow, rain, and fog, there is a high possibility of traffic accidents caused by lack of visibility on actual roads. Although there is a domestic KS standard "KS C 7717" standard for crosswalk lighting as a national standard, it is difficult to adopt or install a product that can actually meet this standard. Therefore, in recent years, there have been more and more attempts to find a realistic lighting environment through various related studies. In order to increase the visibility and minimize the glare, the cut-off light distribution is implemented using a lens and an instrument. However, the angle of vertical light should satisfy 25 cd at 90°, but it is difficult to obtain uniformity, and it is necessary to further lower the vertical angle of light. The color temperature of the LED is used as a road light, and the color temperature of the LED is cool white. However, visibility is good in clear weather, but visibility is deteriorated in bad weather (snow, rain, fog, etc.). To solve these problems, a method of improving the visibility at the time of bad weather is to use a light source of a long wavelength band, but a light source of a long wavelength has a problem of poor visibility in bright weather. In order to improve the problems of such crosswalk illumination, this study proposes a "High Visibility Smart Crosswalk Lighting System". In order to improve pedestrian recognition in accordance with the waiting signal and the walking signal situation, the luminous intensity and wavelength of the crosswalk surface and the walking waiting area lighting should always be maintained at least 24 lx, which is capable of recognizing objects on the road. By using cut-off light distribution to reduce the brightness of vertical angle, it is possible to minimize glare and improve the visibility of drivers and pedestrians. We designed a color-tunable LED module for high uniformity. Simulations have also shown that it is possible to increase the recognition rate for pedestrians on the crosswalk by providing uniform illuminance to the crosswalk area and the atmospheric area. Using this, it is possible to reduce the traffic accident rate on the crosswalk, and the results of this study proved that the studied lighting can satisfy both high level of homogeneity, high efficiency, and low glare. In addition, it has been demonstrated that the circuit characteristics are precisely controlled at high speed. In addition, we have studied and confirmed the high functional lighting that meets the standards of "KS C 7717 LED crosswalk Lighting equipment" through this study. The performance of the prototype was verified. Also, the most difficult cut-off light distribution was satisfied. By studying the method of driving the LED module with multi-channel in the lighting control part, it will be possible to utilize it in various fields of high functional lighting in the future.